/Engine/Source/Runtime/SignalProcessing/Public/DSP/VoiceProcessing.h
InGainTarget is our target running linear gain. InAdaptiveRate is the time it will take to respond to changes in amplitude, in numbers of buffer callbacks. InGainMin is the most we will attenuate the input signal. InGainMax is the most we will amplify the input signal.
FSlowAdaptiveGainControl ( float InGainTarget, int32 InAdaptiveRate, float InGainMin, float InGainMax )